After previously released clips of the show featured Pintauro, 39, talking about his crystal meth use and how he was forced to come out as gay in 1997 after the National Enquirer threatened him, the show itself saved the biggest bombshell for last.

"I wanted to tell you this a long time ago, but I wasn't ready — I'm ready now — that I'm HIV positive, and I have been for 12 years," Pintauro told Winfrey. "It's just a big deal. It's not something that people are talking about right now really."

But Pintauro wants to change that, expressing his desire to be an activist for the LGBT community. He noted that he already "missed the opportunity to be a beacon of light for gay kids who were going through what I was going through because I was outed."

And he also revealed that when he was diagnosed as being HIV positive that he felt a surprising calm.

"It's backwards. You've spent so much time terrified that you're going to get it, and then you have it," he explained. "You don't have to be terrified anymore."

As the previously taped interview was airing, Pintauro posted a photo with his husband of one year, Wil Tabares, on Instagram, writing, "Last meal as a nobody. 😉 first meal as an activist. #lifelovelive."